CN115327272B - Main loop parameter calculation method, system and readable medium of SLCC phase change technology - Google Patents
Main loop parameter calculation method, system and readable medium of SLCC phase change technology Download PDFInfo
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Abstract
The invention belongs to the technical field of power transmission systems, and relates to a main loop parameter calculation method, a main loop parameter calculation system and a main loop parameter calculation readable medium of an SLCC phase change technology, wherein the main loop parameter calculation method comprises the following steps: according to the circuit equivalent model and the circuit simplified equivalent model, calculating an ideal no-load rated direct-current voltage by a Newton Lafson iteration method; according to the ideal no-load rated direct-current voltage, combining an alternating-current system reactive power control target and a direct-current system angle control target, calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model; judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, otherwise, modifying the parameter, and then carrying out the steps again until the calculation result of all the parameters is within the preset range. The method can rapidly and accurately calculate the parameters of the sending and receiving end direct current voltage and current, active and reactive power, tap switch gear, SVG reactive output and the like of each power point, and provide reliable data for the type selection of key equipment of a direct current system.
Description
Technical Field
The invention relates to a main loop parameter calculation method, a main loop parameter calculation system and a main loop parameter calculation readable medium for SLCC (Statcom and line commutation converter) phase change technology, and belongs to the technical field of power transmission systems.
Background
The power grid commutation and commutation direct current transmission technology (LCC) is the most applicable direct current transmission technology form in the current national network, and plays an irreplaceable role in the remote and large-capacity transmission field. However, since the LCC dc transmission technology uses thyristors as current converter devices, the following essential drawbacks still exist: (1) Depending on the commutation voltage, the stable operation is difficult under a weak system; (2) A large phase change angle is needed, a large amount of reactive power is consumed, and a large amount of reactive compensation equipment is needed to be input; (3) The reactive equipment circuit breaker has low switching speed, and cannot be flexibly matched with the control of the trigger angle of the thyristor of the direct current system when a fault occurs, so that reactive excess overvoltage of the alternating current system is caused; (4) The risk of commutation failure exists, and aiming at the current multi-circuit direct current collection and feeding into the grid structure of the same alternating current power grid, all direct currents are mutually coupled, so that a plurality of direct current commutation failures can be caused, and accidents are enlarged.
The VSC technology, i.e. the flexible direct current transmission technology, adopts a voltage source type converter formed by fully controlled power electronic devices, so that not only can the output of active power and reactive power be independently controlled, but also the weak system and even the passive system can be supplied with power, a reactive compensation device is not required to be configured, the harmonic wave of the output voltage is small, inter-station communication is not required, and the occupied area, electromagnetic pollution and the like of a converter station are greatly reduced compared with the conventional direct current transmission.
The SLCC converter technology is a newly proposed converter technology with characteristics of a composite voltage source and a current source, and the topology structure of the SLCC converter technology is shown in fig. 1, so that LCC and VSC performance optimization and upgrading can be realized. The method comprises the following steps: (1) The voltage source characteristic is utilized, the dependence on an alternating current system is reduced, the dynamic reactive characteristic is improved, the novel energy island feed is flexibly adapted, the commutation failure risk is reduced, meanwhile, the harmonic pollution of an alternating current power grid is effectively avoided, the equipment stress is greatly reduced, and the safe operation reliability of the equipment is improved; (2) The mature high-capacity power electronic device is adopted, so that the reliability is high, the loss is small, and the capacity scale is not limited; (3) Through coordination control of the voltage source and the current source, the oscillation risk caused by a single voltage source converter is effectively reduced; (4) And the configuration of an alternating current filter is canceled, so that the total occupied area of the converter station is greatly reduced.
The ubiquitous problems of the development of the novel power system include large randomness and volatility of wind power and photovoltaic power generation, small system inertia, difficulty in providing reactive power support for the system by new energy, and the like, the traditional direct current power transmission system faces serious challenges, SLCC is a novel direct current phase-change technology, can have higher adaptability, and leads the direct current technology to realize new upgrading.
As a new technology, the topological structure combines the respective characteristics of the full-control device and the half-control device, is more complex and difficult in terms of control strategy, simulation model construction and the like compared with the prior LCC and VSC direct current transmission technology, but all the bases are firstly to solve perfect system parameters. In the conventional LCC main loop parameter calculation method, because mutual coupling does not exist among variables, parameters such as the ideal control direct-current voltage Udi0, the phase-changing angle, reactive consumption and the like of the converter are usually solved according to the direct-current voltage and the direct-current target current. The main loop parameter calculation of the SLCC converter technology comprises two branches, wherein a plurality of parameters such as valve side voltage, valve side current, SVG branch voltage, SVG reactive power output and the like are deeply coupled with each other, the calculation solving difficulty is very high, the main loop parameter solving is very critical, and the main loop parameter solving directly influences the converter transformation parameter model selection and the calculation of other subsequent primary equipment.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a main loop parameter calculation method, a main loop parameter calculation system and a main loop parameter calculation readable medium of an SLCC phase change technology, which can rapidly and accurately calculate parameters such as a direct current voltage current, active reactive power, a tap switch gear, reactive power output of SVG and the like of a transmitting end and a receiving end of each power point, and provide reliable data for key equipment selection of a direct current system.
In order to achieve the above purpose, the present invention proposes the following technical solutions: a main loop parameter calculation method of SLCC phase change technology comprises the following steps: according to the circuit equivalent model and the circuit simplified equivalent model, calculating an ideal no-load rated direct-current voltage by a Newton Lafson iteration method; according to the ideal no-load rated direct-current voltage, combining an alternating-current system reactive power control target and a direct-current system angle control target, calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model; judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, otherwise, modifying the parameter, and then carrying out the steps again until the calculation result of all the parameters is within the preset range.
Further, the circuit equivalent model comprises a main loop and an SVG branch, the main loop comprises a first alternating current signal source and a converter transformer equivalent impedance, the first alternating current signal source is connected in series with the converter transformer equivalent impedance, and an output end of the converter transformer equivalent impedance is connected with the LCC converter valve; the SVG branch circuit comprises a second alternating current signal source and a connecting reactor inductor, wherein the second alternating current signal source is connected with the connecting reactor inductor in series, and the output end of the connecting reactor inductor is connected with the main loop.
Further, the circuit simplified equivalent model comprises a third alternating current signal source and a synthetic equivalent impedance of the converter transformer and SVG connection impedance, the third alternating current signal source is connected in series with the synthetic equivalent impedance of the converter transformer and SVG connection impedance, and an output end of the synthetic equivalent impedance of the converter transformer and SVG connection impedance is connected with the LCC converter valve.
Further, the calculation method of the ideal no-load rated direct-current voltage comprises the following steps: according to the initial value of the voltage parameter of the grid-connected point, main loop parameters of a circuit simplified equivalent model are carried out; according to the initial value of the voltage parameter of the grid-connected point, main loop parameters of a circuit equivalent model are carried out; according to the initial value of the voltage parameter of the grid-connected point, SVG branch parameters of the circuit equivalent model are carried out; and solving the ideal no-load rated direct-current voltage through iteration according to the main loop parameter of the circuit simplified equivalent model, the main loop parameter of the circuit equivalent model and the SVG branch parameter.
Further, the main loop parameters of the circuit simplified equivalent model include: phase change angle, reactive power consumption and transmission current; the main loop parameters of the circuit equivalent model include: reactive power consumption of converter transformer, network side current and power factor; the SVG branch parameters of the circuit equivalent model comprise: reactive power output of SVG, reactive power consumption of connecting reactor, disconnection reactive power consumption and SVG voltage source voltage.
Further, the calculation method of the main loop parameters in the circuit equivalent model and the circuit simplified equivalent model comprises the following steps: setting the power step length under multiple working conditions and multiple powers and the actual reactive power exchange control value of each power point, and obtaining the main loop parameters in the circuit equivalent model and the circuit simplified equivalent model through the direct current system operation characteristics under the multiple working conditions under the constraint of Newton iteration calculation conditions.
Further, setting reactive exchange control values of direct current power under a full-voltage operation condition, and calculating steady-state parameters of each power point one by one, wherein in the steady-state parameter calculation process, a newton-Lapherson method is adopted to enable F (x) =Q ti-3Iti 2·ω·Lapf-Qt1i,x＝UL, an initial value is set, an iteration step length is set, if F (x 1) =0 occurs, iteration is ended, wherein I represents an nth power point, Q t is SVG reactive output, I t is SVG branch current, L apf is connecting reactor inductance, and U L is SVG grid-connected point voltage.
Further, during a step-down operation condition, setting a step-down coefficient k, setting a reactive exchange control value of direct current power from 0.1-k, and performing steady-state parameter calculation of each power point one by one, wherein in the steady-state parameter calculation process, a newton-radson method is adopted to enable F (x) =q ti-3Iti 2·ω·Lapf-Qt1i, wherein I represents an nth power point, x=u L, an initial value is set, an iteration step length is set, if F (x 1) =0 occurs, iteration is ended, wherein I represents the nth power point, Q t is SVG reactive output, I t is SVG branch current, L apf is connecting reactor inductance, and U L is SVG grid-connected point voltage.
The invention also discloses a main loop parameter calculation system of the SLCC phase-change technology, which comprises: the no-load rated direct-current voltage calculation module is used for calculating an ideal no-load rated direct-current voltage through a Newton Lafset iteration method according to the circuit equivalent model and the circuit simplified equivalent model; the main loop parameter calculation module is used for calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model according to ideal no-load rated direct-current voltage and combining an alternating-current system reactive power control target and a direct-current system angle control target; and the output module is used for judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, and if not, after modifying the parameter, carrying out the steps again until the calculation result of all the parameters is within the preset range.
The invention also discloses a computer readable storage medium, on which a computer program is stored, the computer program being executed by a processor to implement the main loop parameter calculation method of any one of the above SLCC phase-change techniques.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. The invention can rapidly and accurately calculate the parameters of the sending and receiving end direct current voltage and current, active and reactive power, tap switch gear, SVG reactive output and the like of each power point, and provides reliable data for the key equipment selection of the direct current system.
2. The invention overcomes the series technical defects of the traditional LCC direct current transmission technology, solves the problems of high dependence on an alternating current system and poor adaptability under a large-scale new energy collection scene, can effectively inhibit the problems of overvoltage at a transmitting end and low voltage at a receiving end, and reduces the risk of commutation failure; the electric energy quality pollution and oscillation caused by harmonic wave flowing into an alternating current system are avoided; the equipment safety risk caused by frequent actions of the on-load tap-changer and repeated switching of the filter is greatly reduced.
Drawings
FIG. 1 is a schematic diagram of a prior art SLCC converter valve;
FIG. 2 is a schematic diagram of an equivalent model of an SLCC converter valve circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a simplified equivalent model of an SLCC converter valve circuit according to another embodiment of the present invention.
Detailed Description
The invention is depicted in detail by specific examples in order to provide a better understanding of the technical solution of the invention to those skilled in the art. It should be understood, however, that the detailed description is presented only to provide a better understanding of the invention, and should not be taken to limit the invention. In the description of the present invention, it is to be understood that the terminology used is for the purpose of description only and is not to be interpreted as indicating or implying relative importance.
The invention provides a main loop parameter calculation method, a main loop parameter calculation system and a main loop parameter calculation readable medium for an SLCC phase-change technology, which are used for calculating ideal no-load rated direct-current voltage through a Newton Lawson iteration method according to a circuit equivalent model and a circuit simplified equivalent model; calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model; judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, otherwise, modifying the parameter, and then carrying out the steps again until the calculation result of all the parameters is within the preset range. The scheme of the invention can effectively inhibit the problems of overvoltage of the transmitting end and low voltage of the receiving end, and reduce the risk of commutation failure; the electric energy quality pollution and oscillation caused by harmonic wave flowing into an alternating current system are avoided; the equipment safety risk caused by frequent actions of the on-load tap-changer and repeated switching of the filter is greatly reduced. The following describes the invention in detail by way of examples with reference to the accompanying drawings.
Example 1
The embodiment discloses a main loop parameter calculation method of an SLCC phase-change technology, which comprises the following steps:
S1, calculating an ideal no-load rated direct-current voltage through a Newton Lafson iteration method according to a circuit equivalent model and a circuit simplified equivalent model;
The equivalent circuit model is shown in fig. 2, and defines the positive current direction as the alternating current system to the direct current system. The circuit equivalent model comprises a main loop and an SVG branch, wherein the main loop comprises a first alternating current signal source and a converter transformer equivalent impedance, the first alternating current signal source is connected in series with the converter transformer equivalent impedance, and the output end of the converter transformer equivalent impedance is connected with the LCC converter valve; the SVG branch circuit comprises a second alternating current signal source and a connecting reactor inductor, wherein the second alternating current signal source is connected with the connecting reactor inductor in series, and the output end of the connecting reactor inductor is connected with the main loop. Wherein Us in the main loop is the voltage transmitted by the transmitting end alternating current system; i g is the grid side current; p g is active power transmitted by the converter transformer valve side; l r is converter transformer equivalent impedance; q lg is reactive power transmitted by the converter transformer valve side; u L is SVG grid-connected point voltage; i s is converter transformer valve side current; p L and Q L are the active and reactive power, respectively, flowing into the LCC converter valve. In the SVG branch, I t is branch current, and L apf is connecting reactor inductance; q t is SVG reactive power output, and U t is SVG equivalent voltage.
As shown in fig. 3, the simplified circuit equivalent model includes a third ac signal source and a composite equivalent impedance of the converter transformer and the SVG connection impedance, the third ac signal source is connected in series with the composite equivalent impedance of the converter transformer and the SVG connection impedance, and an output end of the composite equivalent impedance of the converter transformer and the SVG connection impedance is connected with the LCC converter valve.
The simplified equivalent model of the circuit is shown in fig. 2, wherein Us, ps and Qs are respectively voltage, active power and reactive power transmitted by the transmitting end alternating current system, and Lx is the synthetic equivalent impedance of the connection impedance of the converter transformer and the SVG. I s is converter transformer valve side current; u L is SVG grid-connected point voltage; p L and Q L are the active and reactive power, respectively, flowing into the LCC converter valve. The same equivalent model applies to the receiving end. Only in the following, the additions R and I represent the sending end and the receiving end, respectively.
The calculation method of the ideal no-load rated direct-current voltage comprises the following steps:
S1.1, setting initial values of parameters of the grid-connected point voltage U L, and calculating the rated ideal no-load direct-current voltage U di0N of the converter station by Newton iteration according to the known active power, reactive power, direct-current voltage, direct-current and converter transformer equivalent impedance of the direct-current system.
S1.2, according to the initial value of the voltage parameter of the grid-connected point, performing main loop parameters of a circuit simplified equivalent model; the main loop parameters of the circuit simplified equivalent model include: phase change angle, reactive power consumption and transfer current.
The equivalent impedance Lx calculation formula is:
The calculation formula of the ideal no-load voltage U di02 of the direct current system is as follows
Wherein n is 12 pulses.
Phase change angle μ calculation
μ＝acos(cosα-6·100·Lx·Id/Udi02)-α (3)
Integral reactive power consumption of converter device
Integral power factor of converter valve device
Converter valve side current Is
S1.3, carrying out main loop parameters of a circuit equivalent model according to initial values of grid-connected point voltage parameters; the main loop parameters of the circuit equivalent model include: reactive power consumption of converter transformer, network side current and power factor;
Converter transformer current Ig
(PS+QS)2+(Qs-3/2·Lr·Ig 2)2＝(3/2·UL·Ig)2
Converter transformer branch power factor
θvgvi＝atan(Qg/Pg)
Current phase of converter transformer branch
θig＝θvg-θvgvi
Θ vg is the valve side voltage phase angle, taking the net side voltage angle as the starting angle, 0. Reactive power consumption of converter transformer impedance was also calculated:
Q_Lg＝3*ω*Lr*Ig*Ig/2
reactive power through converter transformer impedance
QLg＝Qg-Q_Lg
Converter transformer branch grid-connected point power factor
Grid-connected point voltage phase angle of converter transformer branch
θVL＝θVLvi+θig
S1.4, according to the initial value of the voltage parameter of the grid-connected point, SVG branch parameters of a circuit equivalent model are carried out; the SVG branch of the circuit equivalent model comprises: reactive power output of SVG, reactive power consumption of connecting reactor, disconnection reactive power consumption and SVG voltage source voltage.
Current phase of SVG branch
θis＝θVL-atan(QL/Ps)
Voltage phase of SVG equivalent voltage source
θvs＝θis+atan(Qs/Ps) (8)
Voltage amplitude of SVG equivalent voltage source
Current amplitude of SVG branch
SVG branch outlet reactive power output
Qt＝Qg-(QLg-QL) (11)
SVG voltage source reactive power output
S1.5, the ideal no-load rated direct-current voltage is solved through iteration according to the main loop parameters of the circuit simplified equivalent model, the main loop parameters of the circuit equivalent model and SVG branch parameters.
S2, calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model according to an ideal no-load rated direct-current voltage and combining an alternating-current system reactive power control target and a direct-current system angle control target;
The calculation method of the main loop parameters in the circuit equivalent model and the circuit simplified equivalent model comprises the following steps: setting the power step length under multiple working conditions and multiple powers and the actual reactive power exchange control value of each power point, and obtaining the main loop parameters in the circuit equivalent model and the circuit simplified equivalent model through the direct current system operation characteristics under the multiple working conditions under the constraint of Newton iteration calculation conditions.
And setting reactive exchange control values of direct current power from 0.1 to 1.0pu under the full-voltage operation condition, carrying out steady-state parameter calculation of each power point one by one, adopting a Newton Lafson method to enable F (x) =Q ti-3Iti 2·ω·Lapf-Qt1i,x＝UL in the steady-state parameter calculation process, setting an initial value, setting an iteration step length, and if F (x 1) =0, ending the iteration and returning each parameter of the operation characteristic. Wherein I represents an nth power point, Q t is SVG reactive power output, I t is SVG branch current, L apf is connecting reactor inductance, and U L is SVG grid-connected point voltage.
And in the step-down operation working condition, setting the number of the intervals of [0.5,1.0] of step-down coefficients k=0.7, 0.8, 0.9 and the like, setting reactive exchange control values of direct current power from 0.1-k, and carrying out steady-state parameter calculation of each power point one by one, wherein in the steady-state parameter calculation process, a Newton-Lawson method is adopted to enable F (x) =Q ti-3Iti 2·ω·Lapf-Qt1i, wherein I represents the nth power point, x=U L, an initial value is set, an iteration step length is set, and if F (x 1) =0 occurs, iteration is ended, wherein I represents the nth power point, Q t is SVG reactive output, I t is SVG branch current, L apf is connecting reactor inductance, and U L is SVG grid-connected point voltage.
And after the calculation flow of the jth power point under the ith working condition is finished, calculating the operation characteristics of the next power point, after the ideal control voltage of the converter parameters of all the power points and the positions of the converter transformer taps are finished, calculating the (i+1) th power, and after all the results are calculated, storing the calculation results and exiting from operation.
S3, judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, otherwise, modifying the parameter, and then, carrying out the steps again until the calculation result of all the parameters is within the preset range.
The embodiment provides a main loop parameter calculation method of an SLCC (selective liquid crystal composite) phase conversion technology, which is used for guiding complete set design and system operation and control setting of an actual direct current transmission project, and particularly provides steady state operation parameters for converter transformer design, alternating current-direct current filter design and the like of a direct current transmission system in a future large-scale new energy access background.
Example two
Based on the same concept, the embodiment further describes a scheme in the embodiment by a specific example, in the embodiment, the SLCC-HVDC phase conversion technology design is performed by taking domestic +/-800 kV engineering as an example, the rated voltage of the system is 800kV, the monopole transmission power is 4000MW, the rated trigger angle and the rated Guan Duanjiao are 15 degrees, 17 ° degrees, the range of the trigger angle is [12.5 degrees, 17.5 degrees ], the minimum trigger angle is 5 degrees, and the minimum cut-off angle is 12 °. The direct current rated resistance r=9.65Ω, and the engineering receiver-side main loop parameters will be calculated herein.
The transmitting and receiving end SVG selects reactive exchange junction zero of the alternating current system as a control target, at the moment, main loop parameters under the condition that the power of each converter station synchronously increases from 0.1pu to 1.2pu under the working conditions of bipolar full-voltage operation mode, unipolar ground and unipolar metal operation are calculated, and the direct current power, direct current voltage, direct current no-load direct current voltage, triggering angle/off angle, phase angle, active power consumption of the converter and position results of a converter transformer tap are shown in the following tables 1-3.
TABLE 1 double full-pressure main loop operation characteristic table
Table 3 unipolar Metal Primary Loop operation Property table
The transmitting and receiving end SVG selects reactive exchange junction zero of the alternating current system as a control target, a depressurization coefficient k=0.8 is set, at this time, main loop parameters under the condition that the power of each converter station synchronously increases from 0.1pu to 1.2pu under the working conditions of bipolar full-voltage operation mode, monopolar earth and monopolar metal operation are calculated, and the direct current power, direct current voltage, direct current, no-load direct current voltage, triggering angle/off angle, phase angle, active power consumption of the converter and position results of converter transformer taps of each converter station are shown in the following tables 4-6.
TABLE 4 operating characteristics of double geodetic main circuit
Table 4 monopole earth main loop operating characteristics
TABLE 5 unipolar Metal Main Loop operating characteristics
Example III
Based on the same inventive concept, the present embodiment discloses a main loop parameter calculation system of an SLCC phase-change technology, including:
the no-load rated direct-current voltage calculation module is used for calculating an ideal no-load rated direct-current voltage through a Newton Lafset iteration method according to the circuit equivalent model and the circuit simplified equivalent model;
The main loop parameter calculation module is used for calculating main loop parameters in a circuit equivalent model and a circuit simplified equivalent model according to ideal no-load rated direct-current voltage and combining an alternating-current system reactive power control target and a direct-current system angle control target;
And the output module is used for judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, and if not, after modifying the parameter, carrying out the steps again until the calculation result of all the parameters is within the preset range.
Example IV
Based on the same inventive concept, the present embodiment discloses a computer readable storage medium, on which a computer program is stored, the computer program being executed by a processor to implement the main loop parameter calculation method of the SLCC phase inversion technique of any one of the above.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the application without departing from the spirit and scope of the application, which is intended to be covered by the claims. The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily appreciate variations or alternatives within the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.
Claims (10)
1. The main loop parameter calculation method of the SLCC phase change technology is characterized by comprising the following steps of:
According to the circuit equivalent model and the circuit simplified equivalent model, calculating an ideal no-load rated direct-current voltage by a Newton Lafson iteration method;
according to the ideal no-load rated direct-current voltage, combining an alternating-current system reactive power control target and a direct-current system angle control target, calculating main loop parameters in the circuit equivalent model and the circuit simplified equivalent model;
Judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, otherwise, modifying the parameter, and then, carrying out the steps again until the calculation result of all the parameters is within the preset range.
2. The method for calculating the main loop parameters of the SLCC commutation technology according to claim 1, wherein the circuit equivalent model comprises a main loop and an SVG branch, the main loop comprises a first alternating current signal source and a converter transformer equivalent impedance, the first alternating current signal source is connected in series with the converter transformer equivalent impedance, and an output end of the converter transformer equivalent impedance is connected with an LCC converter valve; the SVG branch circuit comprises a second alternating current signal source and a connecting reactor inductor, wherein the second alternating current signal source is connected with the connecting reactor inductor in series, and the output end of the connecting reactor inductor is connected with the main loop.
3. The method for calculating the main loop parameters of the SLCC commutation technology of claim 2, wherein the circuit simplified equivalent model includes a third ac signal source and a combined equivalent impedance of a converter transformer and an SVG connection impedance, the third ac signal source is connected in series with the combined equivalent impedance of the converter transformer and the SVG connection impedance, and an output end of the combined equivalent impedance of the converter transformer and the SVG connection impedance is connected with the LCC converter valve.
4. The main loop parameter calculation method of the SLCC commutation technology of claim 3, wherein the calculation method of the ideal no-load rated dc voltage is:
according to the initial value of the voltage parameter of the grid-connected point, main loop parameter calculation of the circuit simplified equivalent model is carried out;
According to the initial value of the voltage parameter of the grid-connected point, calculating the main loop parameter of the circuit equivalent model;
according to the initial value of the voltage parameter of the grid-connected point, SVG branch parameter calculation of the circuit equivalent model is carried out;
and solving the ideal no-load rated direct-current voltage through iteration according to the main loop parameter of the circuit simplified equivalent model, the main loop parameter of the circuit equivalent model and the SVG branch parameter.
5. The main loop parameter calculation method of SLCC commutation technology of claim 4, wherein the main loop parameters of the circuit simplified equivalent model include: phase change angle, reactive power consumption and transmission current; the main loop parameters of the circuit equivalent model include: reactive power consumption of converter transformer, network side current and power factor; the SVG branch parameters of the circuit equivalent model comprise: reactive power output of SVG, reactive power consumption of connecting reactor, disconnection reactive power consumption and SVG voltage source voltage.
6. The main loop parameter calculation method of the SLCC phase inversion technique according to any one of claims 1 to 5, wherein the main loop parameter calculation method in the circuit equivalent model and the circuit simplified equivalent model is as follows: setting the power step length under multiple working conditions and multiple powers and the actual reactive power exchange control value of each power point, and obtaining the main loop parameters in the circuit equivalent model and the circuit simplified equivalent model through the direct current system operation characteristics under the multiple working conditions under the constraint of Newton iteration calculation conditions.
7. The method for calculating the main loop parameters of the SLCC commutation technology of claim 6, wherein during the full-voltage operation condition, reactive exchange control values of direct current power are set, steady-state parameter calculation of each power point is performed one by one, during the steady-state parameter calculation process, a newton-radson method is adopted, F (x) =q ti-3Iti 2·ω·Lapf-Qt1i,x＝UL, an initial value is set, an iteration step length is set, if F (x 1) =0 occurs, the iteration is ended, wherein I represents an nth power point, Q t is SVG reactive output, I t is SVG branch current, L apf is a connecting reactor inductance, U L is SVG grid-connected point voltage, and ω is an electrical angle in alternating current.
8. The method for calculating the main loop parameters of the SLCC commutation technology of claim 6, wherein during a buck operation condition, a buck coefficient k is set, a reactive exchange control value of direct current power from 0.1-k is set, steady state parameter calculation of each power point is performed one by one, during the steady state parameter calculation process, newton-radson method is adopted, F (x) =q ti-3Iti 2·ω·Lapf-Qt1i, where I represents the nth power point, x=u L, an initial value is set, an iteration step size is set, if F (x 1) =0 occurs, iteration is ended, where I represents the nth power point, Q t is SVG reactive output, I t is SVG branch current, L apf is a connection reactor inductance, U L is SVG grid point voltage, and ω is an electrical angle in alternating current.
9. A main loop parameter computing system of an SLCC commutation technique, comprising:
the no-load rated direct-current voltage calculation module is used for calculating an ideal no-load rated direct-current voltage through a Newton Lafset iteration method according to the circuit equivalent model and the circuit simplified equivalent model;
The main loop parameter calculation module is used for calculating main loop parameters in the circuit equivalent model and the circuit simplified equivalent model according to the ideal no-load rated direct-current voltage and combining an alternating-current system reactive power control target and a direct-current system angle control target;
and the output module is used for judging whether the calculation result of the main loop parameter is within a preset range, if so, outputting the calculation result, and if not, after modifying the parameter, carrying out the steps again until the calculation result of all the parameters is within the preset range.
10. A computer readable storage medium having stored thereon a computer program for execution by a processor to implement the main loop parameter calculation method of the SLCC commutation technique of any one of claims 1-8.
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